The present invention relates to penalty brake control systems for railway locomotives and, in particular, to such locomotives employing a straight air-type locomotive brake valve device.
Penalty brake control systems have been typically employed on locomotives having automatic-type brake equipments, such as the well-known, standard 26-L Locomotive Brake Equipment manufactured by the Westinghouse Air Brake Company. This automatic-type brake equipment is employed where a locomotive is used to haul a train of cars, since the locomotive brake valve device operates to vary brake pipe pressure, which in turn controls the car control valves and thereby provides substantially synchronized braking throughout the train.
Locomotives or power cars used as service vehicles, such as track inspection vehicles and the like, are typically single-unit vehicles equipped with a straight air-type brake system, which employs the well-known, standard, SA-2 or SA-7 type brake valve device also manufactured by the Westinghouse Air Brake Company. The straight air-type brake valve device controls brake pressure directly, without regulating a train line control pressure, as in the counterpart 26-type brake valve device. Since these locomotives are not used to haul cars, there is no requirement to provide interrelated locomotive/car control functions, thus making it advantageous to employ a straight air-type brake valve device, because of its lower cost as compared to a 26-type automatic brake valve device.
However, it is desirable to continuously monitor the locomotive operator's alertness and well-being in these single-unit service cars, as well as in locomotives hauling a train of cars.